It has been the endeavor of the industry to reduce visible sidestream smoke which most non-smokers consider to be irritating and offensive. Some of the patents dealing with sidestream are as follows.
U.S. Pat. No. 4,231,377, to W. K. Cline and R. H. Martin is directed to a cellulosic wrapper for a tobacco charge which contains at least 15% magnesium oxide and at least 0.5% of a chemical adjuvant selected from alkali metal acetates, carbonates, citrates, nitrates, and tartrates. Both a smoking product and the method of smoking product preparation are disclosed. Furthermore, the patent discloses that magnesium oxide, as referred to in the patent, includes its hydrate, magnesium hydroxide, and mixtures of magnesium oxide and magnesium hydroxide.
U.S. Pat. No. 4,420,002, to W. K. Cline is directed to a cellulosic wrapper for a tobacco charge which contains 5% to 50% magnesium hydroxide filler having a median particle size less than 10 micrometers and an unreactive magnesium oxide filler. In addition, this patent discloses that best results are achieved by adding the magnesium hydroxide filler to the fiber pulp furnish to achieve an intimate contact between filler and fibers. Both a smoking product and the method of smoking product preparation are described.
U.S. Pat. No. 4,433,697, to W. K. Cline and W. F Owens is directed to a cellulosic wrapper for a smoking article which contains 1% to 5% of a ceramic fiber plus magnesium hydroxide and/or magnesium oxide fillers. The ceramic fibers were selected from a group consisting of polycrystalline alumina, aluminum silicate, and amorphous alumina. Furthermore, this patent discloses that the addition of ceramic fiber provides a more solid ash and even greater sidestream smoke reduction than the prior art. Again, both a smoking product and the method of smoking product preparation are disclosed.
U.S. Pat. No. 4,450,847 to W. F. Owens is directed to a cellulosic wrapper containing amorphous magnesium hydroxide gel freshly precipitated on the fibers of the sheet as a filler, plus unreactive magnesium oxide, calcium carbonate or both as co-filler(s). Furthermore, this patent specifically discloses a wrapper with 2% to 8% by weight of potassium acetate as a chemical adjuvant. A key disclosure in the patent pertains to the physical characteristics of an "amorphous gel of magnesium hydroxide" and the manner in which deposition of said gel on the fiber or paper provides more intimate contact and complete coverage of the paper fibers during in situ precipitation. In addition to the wrapper, itself, both a smoking product and the method of smoking product preparation are disclosed.
In a co-pending concurrently filed application by R. H. Martin, there is disclosed a cellulosic wrapper containing up to 15% precipitated magnesium hydroxide filler, up to 25% particulate magnesium hydroxide filler, 0% to 10% calcium carbonate filler, and up to 5% by weight of sodium and potassium acetate burning chemicals. Furthermore, the optimum median particle size of the particulate magnesium hydroxide is a relatively large 15 micrometers. This large particle size would not be expected by "one skilled in the art". A reduction in sidestream particulate delivery rate of up to 80% is disclosed. A cigarette which exhibits a 70% or greater reduction in sidestream particulate smoke is perceived by an observer as producing little, if any, sidestream smoke during static burning.